Memorial day is a time to remember veterans killed in the line of service. These spaceflight heroes deserve to be remembered, too. — Exploring new territory is always costly.

It’s been 100 years since we discovered that the Universe was expanding. But if it’s expanding, then what is it expanding into? — For nearly 60 years, the Big Bang has reigned supreme as our most successful theory as far as explaining our cosmic origins goes. Beginning from a hot, dense, matter-and-radiation-rich state, the Universe has expanded, cooled, and gravitated ever since. As it evolved, it formed protons and neutrons, the first light…

If our Universe were born a little differently, there wouldn’t have been any planets, stars, galaxies, or chemically interesting reactions. — 13.8 billion years ago, what we know today as our Universe began with the hot Big Bang. Filled with matter, antimatter and radiation in an almost uniform fashion, it expanded and gravitated in nearly perfect balance. As the Universe cooled, the matter and antimatter annihilated away, leaving a tiny, minuscule…

Across all wavelengths of light, the Sun is brighter than the Moon. Until we went to the highest energies, and saw a gamma-ray surprise. — If you look at all the objects in Earth’s skies, both natural and artificial, it should come as no surprise that the Sun is the brightest object of all. The Sun, after all, produces its own light, powered by nuclear fusion in its core. That core-generated energy not only holds…

Einstein’s most famous equation is E = mc², which describes the rest mass energy inherent to particles. But motion matters for energy, too. — One of the most profound insights to come about in all of physics has been what’s easily Einstein’s most famous equation: E = mc². Quiet simply, it states that energy is equal to an object’s mass multiplied by the speed of light squared. This simple-seeming mathematical relation holds an enormous…

A surprising JWST discovery around Fomalhaut has a different, superior explanation: not a great dust cloud, but a mere background object. — One of the nearest, brightest stars to us, Fomalhaut, is a remarkable system.

Massive objects like black holes, stars, and rogue planets routinely pass near our Solar System. An ensuing comet storm could destroy us. — Although the Universe is absolutely filled with wondrous objects — including planets, stars, and stellar remnants in practically every one of the several trillion galaxies within the observable cosmos — the distances separating the stars and galaxies from one another are truly tremendous. Even though there are, by some estimates…

When the Universe was first born, the ingredients necessary for life were nowhere to be found. Only our “lucky stars” enabled our existence. — Here on Earth, our planet practically overflows with life. After upwards of 4 billion years of unbroken biological activity on our world, life has spread to practically every niche of our planet’s surface, from the deepest depths of the ocean trenches to interiors of volcanic craters to nearly boiling, acidic…

Some say that the Sun is a green-yellow color, but our human eyes see it as white, or yellow-to-red during sunset. What color is it really? — If there’s one instance where “seeing is believing,” it’s got to be wherever human eyes actually perceive the light that enters them. After all, it’s the very definition of what it means, in human terms, for us to see anything. …